Active Probe, Schematic Included

Рет қаралды 100,690

Күн бұрын

This is a 1:1 RF active probe that I designed for a specific use. If your working on any RF related circuits that require very light coupling, this may benefit you.

Пікірлер: 361

@MrPatdeeee Жыл бұрын

In 91 yrs of my life; I have never seen another like Paul. He is truly a "Cut-Above". Thanks Kind Sir for sharing your talents with us.

@MrCarlsonsLab Жыл бұрын

Thanks for your kind comment Pat!

@akepatinagaraju8564 2 ай бұрын

Great man

@aicisha 4 жыл бұрын

I hope this guy works for a respectable testgear company and he is paid a lot for his work, cause he has a huge bag of knowledge!

@radioguy19510 Жыл бұрын

He's worth whatever he's paid.

@dffabryr 3 жыл бұрын

Amazing Paul, your explanations are crystal clear, your English accent and the talking speed are so comfortable. Again Paul, thank you very much for your videos, I hope to support you in the near future.

@MrCarlsonsLab 3 жыл бұрын

Many thanks!

@d2sfavs 16 күн бұрын

thats so neat how gifted you are with electronics.

@gkruntz 7 жыл бұрын

I just love your lab, Mr. Carlson. :) Thanks for sharing.

@bloguetronica 4 жыл бұрын

Great design, Mr Carlson! It takes a lot of knowledge and experience to do this.

@celtichongy 5 жыл бұрын

Always professional and a joy to watch.

@saturn5tony 8 жыл бұрын

Thanks for sharing Paul, your lab makes me happy! This probe is awesome.

@MrCarlsonsLab 8 жыл бұрын

+saturn5tony Thanks Tony! Glad you enjoyed the video.

@gregagore8056 6 жыл бұрын

Another excellent and interesting video! Thank you Mr. Carlson

@darqen271 8 жыл бұрын

Wow, such a simple design for such a great tool. Thanks for all the insight.

@MrCarlsonsLab 8 жыл бұрын

+Justin L. Your welcome Justin!

@GingerBeker 7 жыл бұрын

great video....i learn a lot of stuff every time i see your videos

@MichaelLloyd 8 жыл бұрын

Great video. I really liked the impromptu tour of the working lab.

@MrCarlsonsLab 8 жыл бұрын

+Michael Lloyd Thanks Michael!

@coasterbrookie 11 ай бұрын

Hi Pat. I realize you have a very significant subscriber base so no reply is just fine. I just have to say that your incredible knowledge is such a pleasure to see. Above and beyond that, your kind demeanor is a tribute to you and your life choices. Just found your channel and now I’m going to have to visit everyday for as long as it takes to make it through all your presentations. Take care and thank you for being such a fine gentleman!! Oh and Patreon is a no brainer for your channel! I’ll support your channel through that app . Andy

@g0fvt 8 жыл бұрын

Another excellent video, always impressed by your extremely tidy printed circuits.

@MrCarlsonsLab 8 жыл бұрын

+g0fvt Thanks! That toner transfer method works well.

@themainproblem 8 жыл бұрын

Thanks for all of your efforts. I think a lot of us out here are very grateful.

@MrCarlsonsLab 8 жыл бұрын

+Thema inproblem Your welcome!

@physicsguybrian 8 жыл бұрын

I very much enjoy your videos and you are a wealth of information! Thank you.

@YanickT 7 жыл бұрын

As usual, very interesting , congratulations good video!

@robertgogol289 8 жыл бұрын

Excellent video. "behind the scenes" looks so familiar :) Thank you for sharing knowledge. This is priceless.

@MrCarlsonsLab 8 жыл бұрын

+Robert Gogol Your welcome Robert!

@themainproblem 8 жыл бұрын

Nicely done Paul. You are a superb teacher and I've leaned a lot from you. Greetings from Arizona.

@MrCarlsonsLab 8 жыл бұрын

+Thema inproblem Thanks for the kind words!

@tomaszwota1465 2 жыл бұрын

This is exactly what I need right now, and Mr Carlson delivers! (Yes, I realize it's years later, KZfaq algorithm works in mysterious ways...)

@PelDaddy 8 жыл бұрын

Great video. Love the behind the scenes. Thanks.

@MrCarlsonsLab 8 жыл бұрын

+PelDaddy Glad you enjoyed the video!

@hosseinpirhady8045 5 жыл бұрын

Very interesting presentation. Thanks for sharing.

@JagjitBrawler 8 жыл бұрын

I just found your videos and I LOVE them....please keep building

@MrCarlsonsLab 8 жыл бұрын

Thanks! I will as time permits.

@JagjitBrawler 8 жыл бұрын

Just curious, did you major in EE and are you an EE yourself or is this just a hobby for you. Im a HS student rn but I really want to get into either electronics or coding

@vehasmaa 8 жыл бұрын

Interesting project.. Big thumbs up... Can wait for next videos..

@MrCarlsonsLab 8 жыл бұрын

+Jurva-Markus Vehasmaa Thanks Jurva-Markus!

@Fredy5100 6 жыл бұрын

Nice little probe. But your lab, Mr. Carlson... that is a slice of heaven. I could see myself getting lost there for days and admiring those beautiful test equipment. Magnificent! :) Thanks for your time!

@MrCarlsonsLab 6 жыл бұрын

I'm glad you're enjoying the video's! Thanks for your kind comment.

@esnam6557 8 жыл бұрын

Thank you very much Paul for sharing this nice video with us.

@MrCarlsonsLab 8 жыл бұрын

+esmaeil nam Glad to share Esmaeil :^)

@codydowling1120 7 жыл бұрын

+MrCarlson, thank you so much for this video and for your channel. The content is excellent, presentation is impeccable, and pace/depth/completeness is unlike anything on KZfaq. Kudos and thank you!

@MrCarlsonsLab 7 жыл бұрын

Thanks for your kind words Cody!

@retro80s22 8 жыл бұрын

great video of the skilled work you do But me being very knew to all this rf radio related stuff its still blowing my brain cells to bits ....keep up your brilliant channel ...

@MrCarlsonsLab 8 жыл бұрын

+retro80s Thanks!

@robertcalkjr.8325 8 жыл бұрын

Thanks Paul. It must be nice to have such a great lab!

@MrCarlsonsLab 8 жыл бұрын

+Robert Calk Jr. Thanks Robert!

@aa7ae 5 жыл бұрын

This looks like a fun project and I'd be interested in building one of these. I believe Paul mentioned in one of his recent Patreon videos he may have an updated version of this project in mind. I'll be very interested to see what he might have come up with.

@BruceNitroxpro 6 жыл бұрын

I would enjoy knowing how you distribute power to all your test gear... especially the grounding system... as well as protection for over voltage between and during work sessions. Consider a video on that subject! Thank you!

@CharlieTechie 8 жыл бұрын

Enjoyed the extra video at the end, I think most of our shops get messy when working on a project. Glad to know your human. 😀

@MrCarlsonsLab 8 жыл бұрын

+Chuck Legg LOL, thanks Chuck!

@garybevis8691 6 жыл бұрын

Dear Paul, you seem to lead a charmed life full of horse shoes. " I just happened to have an input probe with an adjustable cap floating around in my stuff." The packrat in me is envious of your awesome collection of gear. Well done my good man, well done. My grandfather, who lived thru the depression, impressed upon me the value of repair and to never, never, throw away something you might someday use.

@MrCarlsonsLab 6 жыл бұрын

Thanks for your kind comment Gary!

@johnwest7993 2 жыл бұрын

I too have a 3585B, my favorite pies of test equipment, and it is Heaven for working on HF rigs and designs, as well as audio and high frequency vibration analysis.

@mlentsch 8 жыл бұрын

Really good info. Thanks, Paul!

@MrCarlsonsLab 8 жыл бұрын

+Mike Lentsch Your welcome Mike!

@notionSunday 8 жыл бұрын

Great vid. Thanks for showing round the lab.....looks like a scene from an old Vincent Price movie.

@MrCarlsonsLab 8 жыл бұрын

+notionSunday LOL, Thanks!

@ShaunakDe 8 жыл бұрын

I loved trying to follow along to this one!

@MrCarlsonsLab 8 жыл бұрын

+Shaunak De Glad you enjoyed!

@SyedRizvii 8 жыл бұрын

A lot to take from this great video. Would be nice if you could start a series like fundamental Wednesday or some day on RF stuff, loads to learn from. Specially for those who are more into embedded, power or controls world. Great work!

@MrCarlsonsLab 8 жыл бұрын

+Syed Mazahir Rizvi Thanks for your input Syed!

@darnelwashinton1295 2 жыл бұрын

Wonderful, thanks for the clear explanation!

@MrCarlsonsLab 2 жыл бұрын

You're very welcome!

@cuban9splat 7 жыл бұрын

I feel MUCH better about how cluttered my shop gets when building a project. Although, your "messy" lab looks better than my lab when organized LOL. Thank you!

@MrCarlsonsLab 7 жыл бұрын

Glad you enjoyed!

@hemanthkumarreddymedapati5887 6 жыл бұрын

That's wonderful design....... Keep going.... :)

@cbranalli 6 жыл бұрын

i refrain from skipping ads on your channel - although i do kill the annoying audio. my way of expressing respect and gratitude to you.

@MrCarlsonsLab 6 жыл бұрын

Thanks!

@martinborman4195 7 жыл бұрын

Oh, okay, now I see what is going on. Had to rush out for a while and missed the last part. Caught up now. Thanks.

@TheRadioShop 8 жыл бұрын

Paul, Wow! that was pretty amazing. I love the way you explain every step along the way. And the circuit you built is very clever. Also like the way you utilize every piece of test gear. I am also looking for another spectrum analyzer. Really in the need for a more modern one with tracking generator. The old IFR 1200 just does not cut it since there is not tracking gen. he option is about a grand but still no onscreen display. I want to be able to do some V/UHF duplexer tuning. Plus want to homebrew a 4 cavity VHF duplexer :)Great job as always my friend.

@MrCarlsonsLab 8 жыл бұрын

+The Radio Shop Thanks Buddy! That IFR 1200 is still a real neat piece of equipment. Take care!

@gortnewton4765 6 жыл бұрын

Excellent video, as usual, thank you Mr. Carlson.

@MrCarlsonsLab 6 жыл бұрын

You're Welcome Gort!

@TRXLab 8 жыл бұрын

Excellent job Paul! really all thumps up as I exactly know what it means to do a build like this. wish I had a bit more time.... Take care and talk to you soon 73

@MrCarlsonsLab 8 жыл бұрын

+TRXBench Thanks Peter!

@poesboes 6 жыл бұрын

Fantastic project and again an excellent talk! Thanks for sharing! Just one question: why not have the runner of the 1k connected to the minus input of the opamp and the high end towards the output?

@seemeknowme 4 жыл бұрын

I love all your videos, Paul! You've taught me a lot! This week I plan to build a couple of your spectrum analyser protection devices to use with my HP3585A to align my SP-600 IFs. By the way, has anyone ever told you that you look like Vinzenz Kiefer?!

@user-wv9js5cy7t 2 жыл бұрын

Great job, congratulations. I would like to see an active probe for a wider band.

@charlesderyl7542 6 жыл бұрын

Another think to note is about the 1K potentiometer. It do not chage the gain, it just modifie the current in the output transistor. IF instead of that you replace it by, for instance two 1K resistors with the - pin in between, or better you put directly the minus pin at the juction of two output 100 ohms resistors, your gain will be x2. In such a way you could add a 47 ohms resistor at the output. Then loaded by 50 ohms, the gain will be equal to 1 and maybe the small variable capacitor you put add the end will deseapper because the emmiter of the output transistor will be really loaded by 50 ohms and not byt the capacitance of the cable.

@old64goat 8 жыл бұрын

THANKS Paul, another excellent video!

@MrCarlsonsLab 8 жыл бұрын

+old64goat Your welcome!

@dennisqwertyuiop 8 жыл бұрын

Very good work thank you for sharing

@MrCarlsonsLab 8 жыл бұрын

+DENNIS N Your welcome Dennis!

@W1RMD 2 жыл бұрын

Great one! Thanks!

@SignalViewRadios 8 жыл бұрын

Im sure you had pleanty of offers,your a smart person wish i had your brains.

@RupertHandford 8 жыл бұрын

Paul, fantastic project as always. Would love to get a SA one day (or repair one).

@MrCarlsonsLab 8 жыл бұрын

+rupert handford Thanks Rupert!

@martynasmirauskas6977 8 жыл бұрын

I can't believe you have only 20k subscribers. Information on your channel is priceless. Dave from eevblog could learn from you and still his channel is larger. It is not fare.

@cny02253 8 жыл бұрын

Paul is much more hands on, analog and RF oriented than Dave. Dave has teardowns and explains newer tech from a very armchair and consumer perspective but Paul is more oriented to people who actually do build, are hams, are advanced experimenters etc.

@robertcalkjr.8325 8 жыл бұрын

+Martynas Mirauskas Yeah, and Paul doesn't attack the personal beliefs of people. Which wouldn't be so bad if someone did, as long as they provide some basis or facts for their accusations. But as far as I'm concerned, to call someone stupid for their beliefs and not provide any facts to back it up, is the hallmark of lunacy.

@rubusroo68 8 жыл бұрын

+Martynas Mirauskas big difference in output. Mr Carlson is far more detailed, he's like +TheSignalPathBlog Dave is just entertainment.

@mrjohhhnnnyyy5797 8 жыл бұрын

+cny02253 I don't consider myself as an 'advanced tinkerer', but I just love the amount of detail in Paul's in-depth videos. Alan (w2aew) also provides great explanations, I learned heck of a lot from his vids; at the end - Dave is like a pop music, has a larger audience, but not as pleasant as other genres; but great for entertainment sake.

@darqen271 8 жыл бұрын

+dr. Chernobyl Dave is knowledgable, but he is spoiled by all the freebies and money he gets for reviewing products.

@Daniel-ib5bx 8 жыл бұрын

I like the sound of the probe you are talking about at 9:00. This was a great video a learned a lot as always. Thank you so much for all the hard work and effort you put into these videos. You make learning a pleasure.

@Daniel-ib5bx 8 жыл бұрын

Nice lab!

@MrCarlsonsLab 8 жыл бұрын

+Daniel Rogers Thanks Daniel!

@karlmartell9279 Жыл бұрын

My wife collects closets full of clothes but this gear is really worth it!

@darqen271 8 жыл бұрын

Amazing stuff! Love your lab.

@MrCarlsonsLab 8 жыл бұрын

+Justin L. Thanks Justin!

@christophschuermann6512 6 жыл бұрын

I have got the impression that you love measurement equipment, and dont need to think about room temperature in wintertime....

@hankus253 8 жыл бұрын

Very well presented Paul. I liked the comparisons you used in the circuit design explanation for us tube guys. Every little bit helps thank you.

@MrCarlsonsLab 8 жыл бұрын

+hankus253 Thanks Hank!

@tedinfr 5 жыл бұрын

I'm curious to know how the 1M resistor on the input of the op amp is determined. Thanks.

@mohangurunathan8634 6 жыл бұрын

Hi, great video. I am wondering, why the need for the source-follower FET on the input stage? Couldn't you AC couple the probe tip directly to the LT1812 input? Seems like this would avoid some potential bandwidth loss and gain uncertainty in going through the FET. Why is the FET stage needed?

@senohpi 8 жыл бұрын

Great video and a very good looking soldering!

@MrCarlsonsLab 8 жыл бұрын

+senohpi Thanks!

@call5sam 6 жыл бұрын

Great video! What electronic design and layout tools do you use?

@vk2wgw 8 жыл бұрын

Isn't it amazing how everyone knows where everything is in their labs but search the kitchen for a mug to make coffee.. hihi P.S I am learning so much from you videos, thank you. vk2wgw

@MrCarlsonsLab 8 жыл бұрын

+Glenn Wilson Glad your enjoying Glenn!

@barbara217 6 жыл бұрын

Great video - THX!

@kevincozens6837 6 жыл бұрын

The active probe would be a nice and useful item to have in my collection of test gear. I checked eBay to get an idea on the price of an HP 3585B. I found one but the seller wanted more than the price of a new Rigol DSA815-TG. :P One of these days I would like to buy a spectrum analyzer. Spectrum analyzers are rather expensive beasts so I'm more likely to have a go at making a basic one from scratch. I don't need one that covers more than about 0 to 500MHz.

@Thesignalpath 7 жыл бұрын

One thing to note here is that the output impedance of this circuit is not 50 Ohms. It is in fact very small, even smaller than the re of the bipolar because of the shunt feedback from the Opamp. You need a series resistor at the emitter of the bipolar to the output. It would reduce the dynamic range, but provide improved frequency response.

@MrCarlsonsLab 7 жыл бұрын

There are actually quite a few reasons I built the probe in this manor. Normally, I would add that 49.9 Ohm resistor between the emitter and the cable center conductor. I could write a book at this point, right down to the differences in the op-amps (same part #, different results) One of the major reasons was that dynamic range reduction. This probe originally had a specific intention that can be viewed in the CRF-320 video. The probe was to be flat, and unity gain (or close too) within a small spectrum, adding that resistor complicated matters, found through experimentation. Thanks for stopping by, you have an interesting channel as well!

@Thesignalpath 7 жыл бұрын

Thanks! I assumed that you were already aware of the output impedance. The comment was meant for someone who may be skipping through the video and would mistakenly think that the resistors at the emitter would provide 50-Ohm termination. Great work, your patience in your restoration videos is admirable!

@christophschuermann6512 6 жыл бұрын

Mr Carlson's Lab first of all: great video! I undestand both of your explanations regarding the output impedance. If you make a sweep with a 50 Ohm generator into the output of the circuit with the input shorted (50 Ohm would also work ;-) ) you may get surprised. Its all about the flatness of the whole system. Best regards and thanks for your great work!

@relikfinland 5 жыл бұрын

What would you recommend as a replacement for the fet? What charasteristics should I be looking at when picking a replacement for this spesific fet? Thanks you, awesome clip!

@danielbjohnson 8 жыл бұрын

Hi Mr Carlson, good video. You forgot to mention I think that the inductor blocks RF from leaking out your DC path. I am not familiar with the two gate FET. I understand that you can hook it up; to build some advanced gain circuit, but why did you pull the gate to the drain instead of the gates together?

@MrCarlsonsLab 8 жыл бұрын

+Daniel Johnson Richard is correct, the second gate is commonly used for gain control or mixing. Since I'm using this as a source follower, I just tie the 2nd gate to the drain.

@TheRangerDale 8 жыл бұрын

Paul, fantastic, and just what I was working on RF Probe, But wasn't keeping those Tol., Sorta Got a Chuckle, at the ending sweep of camera wondering if the little Young lady came in the Door and seen it , What her words would be? lol lol Yea just a little project what it can do to your Bench area lol Yes enjoyed it and saved this one for future Special RF Probe I may need . Yes keep them coming , man the hits on you unbelievable. 73's .

@MrCarlsonsLab 8 жыл бұрын

+Ranger Dale Thanks for the kind comment! Glad you enjoyed Dale.

@kevinszabo7035 Жыл бұрын

Thank you for the excellent video Mr Carlson. I see that your probe will have very light loading on the circuit under test. Did you ever quantify the input impedance of your probe? X megohms and Y picofarads? Thank you

@rciancia 8 жыл бұрын

Your video series should be a show on the Discovery channel. Seriously - many people learn from you (myself included). Many more can too :)

@MrCarlsonsLab 8 жыл бұрын

+Ron C Thanks for the kind comment Ron!

@robertriley4140 8 жыл бұрын

Is there any way of getting a copy of the drawn PCB design, as it is so critical for a successful (first time) outcome? regards Bob_R

@tkarlmann 7 жыл бұрын

Wow! I'd give you Thumbs Up, as usual, just for showing all the Equipment you have! To the rf probe: Did you experiment with the number of connections you placed stitching the two sides pf the PCB together? Common practice for normal, non-rf, circuitry would place many stitching vias along those edges. Thoughts on the possible effects of more side-side connections?

@MrCarlsonsLab 7 жыл бұрын

Hi. If this probe was to go higher than it's intention (UHF+) Then the "stitching" would be needed. This is only intended for the HF region.

@franzgol 8 жыл бұрын

Actually, for headphone users the camera's microphone seems far better because is not picking up all of the breath-in noises :) anyway greath channel, you're a fantastic teacher.

@MrCarlsonsLab 8 жыл бұрын

+franzgol Thanks for your input!

@danielstimpson7792 8 жыл бұрын

Very good video..

@MrCarlsonsLab 8 жыл бұрын

+Daniel Stimpson Thanks Daniel!

@cny02253 8 жыл бұрын

Very good Paul! Wondering if you have ever thought about getting a file sharing account of some sort to post PDF's (like Alan W2AEW does) or drawings, schematics, PCB art, etc.? Anyway, instead of using a SG, one could hook this up to a sweep generator and look at the output in X-Y mode on an oscilloscope, sorta like we can with filters? (Keeping our impedance ducks in a row of course.)

@MrCarlsonsLab 8 жыл бұрын

+cny02253 Thanks! I'm thinking of setting something up (file sharing) But it's all about time. Using a sweep generator and a scope would be just fine, as long as you know your 3DB down point, and your test set up is flat.

@claudioi2ndt313 5 жыл бұрын

hi Mr Carlson! is it possible to have a copy 1:1 of the printed circuit board? THANKS! and...Happy New Year! i2NDT Claudio

@jose_simon 8 жыл бұрын

Cant beat Mr Carlson's explanations. Thanks!

@MrCarlsonsLab 8 жыл бұрын

+Ignacio Simón Thanks Ignacio!

@fieldsofomagh 8 жыл бұрын

That flat response for the If's is super. What kind of microscope do you use ? Looks ideal for work on small circuitry.Very well kitted out lab an when ya see a mess ya know there's good R&D goin on.

@MrCarlsonsLab 8 жыл бұрын

+Tom OConnor Thanks Tom! The trinocular microscope came from a university, unfortunately the name is no where to be seen.

@ytrewq6789 8 жыл бұрын

Thank you!....., You (yet again), just saved me a pile of trouble having to do this myself from scratch!....... I just haft to figure out where to etch your name?, on the board of my build of your probe lol.

@MrCarlsonsLab 8 жыл бұрын

+ytrewq6789 Your welcome! LOL, my name is to big for the board size :^)

@johnweegenaar7314 5 жыл бұрын

Hi there Your probe is amazing . I do alot of audio work for a hobby . Do you have a kit of this probe mainly for the circuit board as this would be great to build . Thanks John

@BruceNitroxpro 5 жыл бұрын

John Weegenaar, Paul has been asked if he has kits or boards of any of his projects and his answer is usually a 'no' with some sort of suggestion that the maker should make boards themself... in other words, "NO."

@markg1051 8 жыл бұрын

Great video, love the emphasis on correct termination. Trying to figure the reason for the 2 dislikes, must be your use of the word "linear" to describe the slight slope in the response on either side of the flat band. Or maybe, they are people with a very short span of attention, which is quite possible. Re the comparison to EEV blog below, this is no BS imparting of knowledge & info, not an entertainment stunt. Best regards Mark G

@nRADRUS 8 жыл бұрын

do not care about dislikes. it is youtube recommendation failed for some persons.

@michaelcruz1434 4 жыл бұрын

It could be they fat fingered it. I did that once, but it tool away my thumbs down when I then hit the thumbs up. People who are threatened because they have no inkling of what Paul’s talking about may downvote just to protect their ego. Mr Carlson has taught me a lot and I expand my mind every time I watch.

@Chipz0r 8 жыл бұрын

Nice vid, thanks . Question tho , what is that huge grey enclosure in the corner ? looks like a 10kw am tx ;)

@MrCarlsonsLab 8 жыл бұрын

+Chipz0r Its an old GATES transmitter :^)

@clytle374 2 жыл бұрын

The 3SK74 are done now, like so many parts.

@amikhimji 8 жыл бұрын

great video thanks

@MrCarlsonsLab 8 жыл бұрын

Your welcome!

@gregorywest2029 8 жыл бұрын

Great Video Paul, How about design a probe to replace the hp84 series rf power sensors, so we can still use these meters. Keep them comming, Greg

@MrCarlsonsLab 8 жыл бұрын

+Gregory West Ya Know, I may just do that. Thanks for your comment!

@andycristea 8 жыл бұрын

Awesome! Can't wait for the next videos!

@MrCarlsonsLab 8 жыл бұрын

+Andy Cristea Thanks Andy!

@sjachim314 8 жыл бұрын

Hi. Great video. Can you help me understand what sets bias of the output transistor? Also why does the combined 50ohm go to ground and not between transistor emitter and the cable?

@MrCarlsonsLab 8 жыл бұрын

+Szymon Jachim Its all about impedance and reflected signals. I will do a video on this in the future. My TDR video may help you understand kzfaq.info/get/bejne/f5eXmbh_zZu0eoU.html

@rtybn2012 8 жыл бұрын

You need a resistor at the E of the BC817, depending on the Re of the sistor which is .026 milliohm /milliamp which is depending on voltage at the E to gnd ~47ohms.

@MrCarlsonsLab 8 жыл бұрын

+Henry Hopkinson There are 4 resistors at the Emitter of the 817, clearly displayed in the schematic.

@rtybn2012 8 жыл бұрын

There should be a resistor in SERIES with the .01mfd capacitor. If you look back into the E of the transistor there is a very low impedance, Re. You need the resistor to match the the 50 ohms termination.

@mikesradiorepair 8 жыл бұрын

Great project Paul. Looks like it turned out very nicely. Hmmm, a project in the 40MHz range. You have my curiosity peaked. :) Would love to get the PCB layout file. Any chance you could forward it? Mike

@MrCarlsonsLab 8 жыл бұрын

+MikesRadioRepair Hi Mike, When I find some spare time, I will set up a file sharing (something or other) :^) The video will be coming soon regarding the restoration. Thanks for your comment!

@terryuren9170 8 жыл бұрын

I am all ways inpressed by your printed circuits board!! Question on the schematic on the op amp on the + side is that side going to erath !! thank you terry

@MrCarlsonsLab 8 жыл бұрын

+terry uren Hi Terry. The plus symbol you see on the op-amp is the non inverting input. The supply connections are not shown.

@richardphillips2405 6 жыл бұрын

I enjoyed the video. I was wondering how to attach the tracking generator to the circuit that you are aligning so that the tracking generator would be protected. How do you match the impedance of the tracking generator to the input of the circuit you are testing. Is it okay to connect a signal generator with a low output impedance to the input of the dut that has a high impedance without any matching? Thanks.

@MrCarlsonsLab 6 жыл бұрын

Hi Richard. In most cases, a terminated cable at 50 Ohms, and a capacitor in the Pico Farads somewhere is usually good enough for coupling the signal gen or tracking gen to any receiver. Never couple your test gear to a receiver without a DC block (that pF capacitor) or you may damage the output sections of your tracking gen or signal gen. I designed a protection circuit for this purpose, see this video: kzfaq.info/get/bejne/e7p7rK50l8DOXYE.html

@sivalley 6 жыл бұрын

Take a drink every time he says "flat". ;)

@MatthewHolevinski 6 жыл бұрын

I did

@freqcy 7 жыл бұрын

Great tutorial, could you give us a study on building another prove that can be used up to 1 Ghz for use with a oscilloscope with input impedance of 50 ohms Nic

@jafinch78 7 жыл бұрын

Yes, with the active scopes... I've read we should use x3 or x5 or more frequency probe of the frequency of your oscilloscope. I'll have to watch this since I haven't yet and got carried away reading the comments. May be a clue in the schematics where something can be changed say like you can add a potentiometer to see the effect on the circuit Hz. I know when you get into the Ghz range circuits get strange and board design even looks unique with interesting shapes eched into the boards as filters and you almost have to comprehend electronic component design and the board as an antenna with your board design, i.e. each component trace is an antenna with a SWR, impedance, coupling, etc. for optimal design. Interesting learning from a chemist, programmer and project leader background perspective. Mr. Carlson definitely is the best I've watched so far in explaining in detail electronics on a small budget.

@wadehicks9270 8 жыл бұрын

Good info.

@MrCarlsonsLab 8 жыл бұрын

+wade hicks Thanks Wade!

@hwatson069 4 жыл бұрын

I am wondering if the gain control is shown correctly... Normally, I would expect that the top of the potentiometer would be connected to the output emitter follower and the "slider" would be connected to the inverting input...